Dogs and diamonds took center stage yesterday at day two of Sotheby’s Brooke Astor auction, where the late socialite’s most extravagant effects were sold, raising nearly $19 million for her favorite charities.

After shattering presale estimates with brisk sales of Asian furnishings, signed paintings and sparkling silverware, the auction closed with a dramatic bidding war over Lot 898, a platinum, emerald and diamond ring that sold for $1.2 million.

The final bid came after a cutthroat back-and-forth between a buyer on the phone and a couple in the audience. The determined couple won.

The ring, which was estimated to sell at $150,000, outsold even the breathtaking emerald necklace Astor wore in 1969 when she met President Lyndon Johnson at a dinner dance in his honor at The Plaza Hotel.

Bidders got an intimate look at Astor’s lavish lifestyle, particularly her love of dogs, which she had on display in both her elegant homes.

Seventy-three lots of canine paintings, including more than a dozen that lined the wall above a circular staircase at Holly Hill, her Westchester estate, sold for $816,130.

Socialite Armene Milliken, who knew Astor for more than 20 years, said her friend gave her some things before she died, and joked that she should have sold some items at the auction.

“She was fun,” Milliken said. “She was a wonderful character. She was very generous. “It’s too bad about the legal issues.”

“I’ve loved period pieces since I was a little girl,” Guinness said.

The money raised from the two-day auction will benefit several institutions and charities, including the New York Public Library and the Metropolitan Museum of Art, under a settlement negotiated by the state Attorney General’s Office.

The collection had been expected to fetch just $6 million to $9 million.

The auction comes after a nasty family feud involving her only son, Anthony.

The five-year dispute ended in March with a settlement that freed $100 million for her charities and cut by more than half the amount going to Anthony Marshall, who was convicted of taking advantage of his mother’s dementia and making changes to her will. Marshall has appealed.

Astor died in 2007 at age 105 after spending much of her life putting the fortune left to her by third husband Vincent Astor to good use.

In 1998, she earned a Presidential Medal of Freedom, the nation’s highest civilian honor.